Explore the full potential of C++ by mastering the standard library.

Become a C++ Programmer

The C++ standard library is a collection of all the tools and utilities available in C++. It received its latest update in 2017, known as C++17. The update introduces many new features that further optimize our code. This module will help us fully grasp C++ and use it to its full potential.

C++ Standard Library

## Input

You can read in C++ in two way from the input stream: Formatted with the extractor `>>` and unformatted with explicit methods. 

### Formatted Input
The extraction operator `>>` 

* is predefined for all built-in types and strings,
* can be implemented for [user-defined data types](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/user-defined-data-types/),
* can be configured by format specifiers. 

> 🔑 **std::cin ignores by default leading whitespace**
>```C++
>#include <iostream>
>//...
>int a, b;
>std::cout << "Two natural numbers: " << std::endl;
>std::cin >> a >> b; // < 2000 11>
>std::cout << "a: " << a << " b: " << b;

### Unformatted Input
There are many methods for the unformatted input from an input stream `is`:

| **Method** | **Description** | 
|-|-|
| `is.get(ch)` | Reads one character into `ch`. |
| `is.get(buf, num)` | Reads at most `num` characters into the buffer `buf`. |
| `is.getline(buf, num[, delim])` | Reads at most `num` characters into the buffer `buf`. Uses optionally the line-delimiter `delim` (default `\n`). |
| `is.gcount()` | Returns the number of characters that were last extracted from `is` by an unformatted operation. |
| `is.ignore(streamsize sz= 1, int delim= end-of-file)` | Ignores `sz` characters until `delim`. |
| `is.peek()` | Gets one characters from `is` without consuming it. |
| `is.unget()` | Pushes the last read character back to `is`. |
| `is.putback(ch)` | Pushes the character `ch` onto the stream `is`. |
 Unformatted input from an input stream 


> 🔑 **std::string has a getline function**
>\
> The [`getline` function](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/input-and-output/) of std::string has a big advantage above the `getline` function of the `istream`. The std::string automatically takes care of its memory. On the contrary, you have to reserve the memory for the buffer `buf` in the `is.get(buf, num)` function.

# Input

You can read in C++ in two way from the input stream: Formatted with the extractor `>>` and unformatted with explicit methods. 

## Formatted Input
The extraction operator `>>` 

* is predefined for all built-in types and strings,
* can be implemented for [user-defined data types](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/user-defined-data-types/),
* can be configured by format specifiers. 

> 🔑 **std::cin ignores by default leading whitespace**
>```C++
>#include <iostream>
>//...
>int a, b;
>std::cout << "Two natural numbers: " << std::endl;
>std::cin >> a >> b; // < 2000 11>
>std::cout << "a: " << a << " b: " << b;

## Unformatted Input
There are many methods for the unformatted input from an input stream `is`:

| **Method** | **Description** | 
|-|-|
| `is.get(ch)` | Reads one character into `ch`. |
| `is.get(buf, num)` | Reads at most `num` characters into the buffer `buf`. |
| `is.getline(buf, num[, delim])` | Reads at most `num` characters into the buffer `buf`. Uses optionally the line-delimiter `delim` (default `\n`). |
| `is.gcount()` | Returns the number of characters that were last extracted from `is` by an unformatted operation. |
| `is.ignore(streamsize sz= 1, int delim= end-of-file)` | Ignores `sz` characters until `delim`. |
| `is.peek()` | Gets one characters from `is` without consuming it. |
| `is.unget()` | Pushes the last read character back to `is`. |
| `is.putback(ch)` | Pushes the character `ch` onto the stream `is`. |
 Unformatted input from an input stream 


> 🔑 **std::string has a getline function**
>\
> The [`getline` function](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/input-and-output/) of std::string has a big advantage above the `getline` function of the `istream`. The std::string automatically takes care of its memory. On the contrary, you have to reserve the memory for the buffer `buf` in the `is.get(buf, num)` function.

# Input

You can read in C++ in two way from the input stream: Formatted with the extractor `>>` and unformatted with explicit methods. 

## Formatted Input
The extraction operator `>>` 

* is predefined for all built-in types and strings,
* can be implemented for [user-defined data types](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/user-defined-data-types/),
* can be configured by format specifiers. 

> 🔑 **std::cin ignores by default leading whitespace**
>```C++
>#include <iostream>
>//...
>int a, b;
>std::cout << "Two natural numbers: " << std::endl;
>std::cin >> a >> b; // < 2000 11>
>std::cout << "a: " << a << " b: " << b;

## Unformatted Input
There are many methods for the unformatted input from an input stream `is`:

| **Method** | **Description** | 
|-|-|
| `is.get(ch)` | Reads one character into `ch`. |
| `is.get(buf, num)` | Reads at most `num` characters into the buffer `buf`. |
| `is.getline(buf, num[, delim])` | Reads at most `num` characters into the buffer `buf`. Uses optionally the line-delimiter `delim` (default `\n`). |
| `is.gcount()` | Returns the number of characters that were last extracted from `is` by an unformatted operation. |
| `is.ignore(streamsize sz= 1, int delim= end-of-file)` | Ignores `sz` characters until `delim`. |
| `is.peek()` | Gets one characters from `is` without consuming it. |
| `is.unget()` | Pushes the last read character back to `is`. |
| `is.putback(ch)` | Pushes the character `ch` onto the stream `is`. |
 Unformatted input from an input stream 


> 🔑 **std::string has a getline function**
>\
> The [`getline` function](https://www.educative.io/courses/cpp-standard-library-including-cpp-14-and-cpp-17/input-and-output/) of std::string has a big advantage above the `getline` function of the `istream`. The std::string automatically takes care of its memory. On the contrary, you have to reserve the memory for the buffer `buf` in the `is.get(buf, num)` function.

Apart from 'cin' and 'cout', there are many other functions we can use to perform input/output operations.

The Standard Library

Overview

Application of Libraries

Useful Functions

Adaptors for Functions

Pairs and Tuples

Reference Wrappers

Smart Pointers

Type Traits

Time Library

std::any, std::optional, and std::variant

Containers in General

Sequential Containers

Associative Containers in General

Ordered Associative Containers

Unordered Associative Containers

Adaptors for Containers

Iterators

Callable Units

Algorithms

Non-Modifying Algorithms

Modifying Algorithms

More Algorithms

New Algorithms with C++17

Numeric

Strings

String View

Regular Expressions

Input and Output Streams

Conclusion

Input and Output Functions

Input

Formatted Input